Switch construction



Sept' 4, 1962 w. c. PIKE 3,052,774

SWITCH CONSTRUCTION INVENTOR. WILSON C. P KE BY C. 4f- 1 Y Cl. @l

A TTORNEYS Sept. 4, 1962 w..P1Kr-;

SWITCH CONSTRUCTION Filed April l5, 1959 FIQ, 75

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2 Sheets-Sheet 2 IN V EN TOR. W/L S 0N C. PIKE A TTORNEY United States Patent O M 3,052,774 SWITCH CNSTRUCTION Wiison C. Pike, 88 Vineyard Road, Huntington, N.Y. Filed Apr. 13, 1959, Ser. No. 806,032 26 Claims. (Cl. 20G-67) This invention relates to electrical switches, and more particularly to electrical switch designs which can be fabricated in a wide range of sizes including sub-miniature sizes, and which can be furnished with va wide range of contact arrangements.

`Electrical switch devices, particularly in small sizes, are difcult to 4fabricate because of the problems of assembling interacting movable parts in small spaces while providing for suilicient spring pressures to insure efficient electrical contact and protection against mal-functioning under acceleration forces. Also, because most switches require snap action -to insure good operating characteristics and to protect the contacts, relatively intricate toggle or over-centering linkages are used. These linkages tend to be costly and almost invariably are subject to breakdown.

It is, therefore, an object of the present invention to provide an improved electrical switch construction overcoming the above and other disadvantages of conventional designs.

Another object of the invention is to provide Ian electrical switch design which, using modular components, can be assembled in -a relatively wide range of contact combinations and arrangements.

Still another object of the invention is to provide a multiple contact electrical switch assembly having snap switch action without the use of springs and other components which are frequently the basis `for switch breakdown and failure.

Still another object of the invention is to provide an improved electrical switch construction which is adaptable for use with both manual actuators and electro-magnetically driven actuators to establish automatic relay actions.

In accordance rwith the present invention, there is proe vided a switch construction having complementary magnetic parts including a magnetic pole structure having a pair of spaced pole pieces and a magnetic, movable meinber captured within the flux field with at least two positions of equilibrium, i.e. maximum attracting force. 'Ille position which the movable member assumes is controlled by an actuator which is movable to urge the mova'ble member toward either of its stable positions and which engages the member in an unstable support. The actuator preferably takes the form of a knife-edged rocker on `which the movable member rolls to assume its stable positions. If preferred, the magnetic member can be utilized as part of the electrically conducting path between contact abutments which determine its limit positions. Movable contact elements can be interposed between the movable member and the -abutments to eliminate the electrically conducting path through the magnetic member. In order to provide automatic relay action, field coils can be utilized in place of the movable actuator which then becomes a fixed pivot over which the movable member rolls in moving between its bistable positions.

The above and other features and objects of the invention 4will be readily understood having reference to the accompanying drawings in which:

FIGURE l is a view in vertical section taken on the line 1-1 of FIGURE 2 looking in the direction of the arrows of a switch assembly embodying the present invention;

FIGURE 2 is a view in transverse section taken on 3,652,774 Patented Sept. 4, 1962 ICC the line 2 2 of FIGURE l looking in the direction of the arrows;

lFIGURE 3 is a view in transverse section of a switch assembly having a modified contact configuration;

FIGURE 4 is a view in vertical section of a switch assembly embodying a modified actuating linkage;

FIGURE 5 is a view in vertical section of a modified switch construction;

FIGURE 6 is a view in Vertical section illustrating the switch construction embodied in a relay;

tFIGURES 7A and 7B are views in vertical section partly diagrammatic in nature, illustrating another modified switch construction;-

l'FIGURE 8 is a view in perspective of a component of the switch of FIGURES 7A and 7B;

FIGURE 9 is a view in vertical section of a modified switch construction; Aand FIGURE 10 is a view in transverse section taken on the line 10-10 of FIGURE 9 looking in the direction of the arrows.

`Referring to the specification and FIGURES l and 2 in particular, there is illustrated a switch assembly including a casing 10, preferably formed of electrically insulating material such as plastic, and having three terminals, 11a, 11b, and 11e and 11C. Mounted Within the housing 10 is a permanent magnet 12 preferably taking the form of a ceramic magnet which is electrically insulating, although it will be understood that more conventional ferro-magnetic materials such as Alnico V can be used. The magnet 12 is in a generally horseshoe conguration with its pole faces 12a and 12b inwardly inclined. Mounted between the pole faces of the magnet 12 is a constraining or barrier member 13 which in the illustrated arrangement is movable with a pivot shaft 14 so that its upper relatively narrow edge 13a swings `over an arc of approximately ten degrees. In this arrangement the constraining or barrier member is `also a `common electrical contact, as will be described below. Referring only to FIGURE l for purposes of explanation, there are disposed in the chamber 15 above the magnet 12 a pair of contact arms 16a and 16h connected respectively to the terminals 11a and 11b, and freely mounted between the contact arms 16a `and 1Gb and resting on the edge 13a of the member 13 is a ferromagnetic movable member 17, which is circular about an axis normal to the paper as Viewed in FIGURE l, so that it is capable of rolling over the edge 13a. Thus the movable member 17 is positioned or constrained by the member 1'3 and the contact arms 16a and 1Gb while under the influences of the magnetic attraction.

The size of the movable member 17 is such that it wedges between the common contact 13 and either of the contact arms 16a and 1Gb, depending on which Way the common contact is swung. As illustrated in FIG- URE l, an electrical circuit is completed between the terminals 11b and 11C, the common contact 13 having been swung to the left in a counter clockwise direction. To open the circuit between the contacts 11b and 11C and to establish a circuit between the contacts 11a and 11e the actuator and common contact 13 is swung clockwise to the right, driving the movable member A17 to the top of the knife edge 13a, at which point it is unstable, after which it snaps into position between the contact 13 and the contact arm 16a. Thus there is provided by the contacts 16a-b and 13 a snap actuating single pole double switch. The contacts are held closed by the magnetic attraction between the permanent magnet 12 and the magnetic member 17 with wiping action being established each time the contacts close and with extremely high contact pressures obtained due to the inclined surfaces of the contact arms 16a and 16h with respect to a line perpendicular to the oblique pole faces 12a and 12b.

As will be apparent from the specification which follows, various means for actuating the movable common contact 13 can be provided. In FIGURES 2 and 3 the actuator 13 is shifted angularly by means of torque applied to the pivot shaft 14, which driving forces can be applied through any suitable means, i.e. knob (not shown) or a radius arm 14a (FIGURE 2). Other actuating techniques including a rectilinearly movable common contact (FIGURE and an electro-magnetically driven system (FIGURE 6) will be described at a later point.

Referring now to FIGURE 2, it will be seen that the movable member 17 is mounted on an electrically insulated pin 18 by means of an enlarged aperture 17a through its center. The pin carries Ia second movable member 19, also preferably formed of ferro-magnetic material and having an enlarged central opening 19a which also receives the pin 18. The second movable members 18 and 19 are separated by an electrically insulating spacer or washer 20. A second contact el-ement and common contact or actuator 21, duplicating the actuator 13 is also mounted on the torsion pin 14 to turn therewith. Preferably the two actuators 13 and 21 are electrically insulated from the pin 14 by insulating sleeves 13b `and 2lb and are electrically insulated from each other by a spacer 22. A second pair of contact arms, identical to the contact arms 16a-16b of FIGURE 1, are disposed on opposite sides of 'the member 19, only the contact element 23b, having fa terminal 24b, being visible in FIGURE 2 `of the drawing. Thus, there is provided a double pole, double throw switch wherein the action of one pole or side of the switch does not impede the action of the other. This is achieved by providing the clearance between the pin 18 and the ferro-magnetic members 17 and 19 so that relative movement can occur or provide full Wedging and wiping action for each set of contacts. It be understood that additional contact assemblies can be added by providing a wider housing and stacking additional modular units on the insulating pin 18 and the 'actuating pin 14.

Referring to FIGURE 3, there is illustrated a modified arrangement of the switch wherein the common contact memlber or actuator, such as the members 13 and 21 of FIGURES l and 2, is replaced by an electrically insulating member l24 and eliminating that member from the electrical circuit. To this end, there are provided pairs of companion contacts 25a, 25h, 26a, and 2Gb, each corresponding generally -to the Contact arm 16a of FIGURE 1. The pairs of contact arms 25a-25b and 26a-2Gb are bridged respectively by movable members 27 and 28, both being formed of ferro-magnetic material and both being electrically conducting. 'lhe two members 27 and 2,8 are loosely mounted on a common, lelectrically insulating supporting pin 29 and are separated by an electrically insulated spacer 38. The movable members 27, which are circular, are preferably crowned `or transversely rounded on their peripheries, as viewed in FIG- URE 3. In other respects, the Iarrangement of FIGURE 3 generally conforms to that illustrated by FIGURE l so that with the actuating member 24 swung toward the reader, the member 27 will engage the contacts 25a and 25b and the member 28 will engage the contacts 26a and 26b. In each case, the movable member will seek a position, due to the combined effects o-f the crowning and the loose mounting, which achieve maximum contact pressures. As described, there is provided a singlethrow, double-pole switch. It will be understood that either an abutment stop or -a second battery of four contact arms can be disposed in the housing for the other position of stable equilibrium of the members 27 and 28, 4thereby providing in effect a pair of double-pole, double-throw switches, all within an extremely small space.

Referring to FIGURE 4, there is illustrated `a modified switch construction wherein the movable, ferromagnetic member is not utilized in the electrically conducting path. In FIGURE 4, parts which are functionally `equivalent to parts of the switch of FIGURE l, are identified Iby like, primed reference numerals. Pivotally mounted to `the housing `10 on an axis 31 is an electrically conducting common contact member 32 electrically connected to an output terminal 33, as through a flexible coupling (not shown). The two diverging arms 32a and 32b of ythe common contact member 32 are disposed respectively between the contact 11a and the movable member 17 and between the contact 1Gb and the movable member 17. As illustrated in FIGURE 4, the movable member 17' takes the form of a ferro-magnetic ball. In operation, as the actuator 13 is swung either to the right or to the left, the movable member 17 will drive one or the other set of electrical contacts into engagement as it seeks its position of stable equilibrium. It is preferred in the arrangement of FIGURE 4 to use an insulating material for the actuating member 13 or otherwise to insulate the member from the exterior of the switch.

As stated, the shaft 14 on which the actuating member 13 pivots can be driven by manual action. It can also be operated automatically, for example by thermostat 34 in which -a bi-metal element 35 working against a double rock shaft linkage 36 turns the shaft 14. Lost motion between the arms of the rock shaft linkage 36 and the -bi-metal element 3S enables the inherent snap action to occur within the switch body 10.

Referring to FIGURE 5, there is illustrated an arrangement whereby the pivoted or swinging actuator 'and common contact (identified by the numeral 13 in FIGURE l) is replaced by an actuator and common contact element 38 having a knife or narrow edge 38a supporting the movable, ferro-magnetic member and carried in a supporting block 39 which is also a permanent magnet. The supporting block and permanent magnet 39 is mounted on a rectilinearly movable plunger 40 working against `a spring 41. When the plunger 48 is pressed inwardly, the movable member 17 will snap with the contact 16a to close the circuit between the contact and the common contact 38 and to open the circuit between the normally closed contacts 16H-38. By utilizing a sufficiently strong spring 41 this arrangement results in a momentary type single-pole switch for the contacts 38a-16a. It will be understood that multiple momentary contacts can be provided in this switch configuration by applying thereto the multiple or stacked arrangements of FIGURE 2 or 3. Also contact 16h may be used as a normally closed contact or used `as an abutment stop. It will be observed that the working faces of the contacts 16a and lbare inclined to the opposing surfaces of the common contact 38, thereby to facilitate the Wedging and wiping actions described above.

Referring to FIGURE 6, there is illustrated an electromagnetic relay 42, the housing 43 of which is formed with a chamber 44 in which is mounted a permanent magnet 45 through which extends a fixed `or immovable common contact 46 connected to a `terminal 47. If a ceramic, electrically insulating magnet is used, 'the magnet need not be electrically insulated from the contact and its terminal. However, if a ferro-magnetic material is used for the magnet, it is for most pulposes, preferred to insulate the magnet from the electrical circuit. Disposed to the left of the common contact `46 isa moa/able circular member 48, such for example as a steel ball or roller and flanking the member 48 are a pair of inclined contacts 49a and 49h so dimensioned and positioned relative to the fixed contact 46 that the movable member 48 wedges itself therebetween in an efficient electrical contact under the magnetic pull. The movable member 48 is stable on either side of the common contact 46 and to determine on which side the member comes to rest, there are provided a pair of electro-magnetic coils 58a and Sfb associated respectively with the contacts 49a and 49h. In this fashion, a double-throw, and, if desired, polarized relay is established. It will be understood that by changing the spacing and shaping `of one of the contacts, i.e. lthe contact 49h, it is possible to provide an arrangement in which the movable member will remain against the contact 4911 only While the coil Stb is energized. In such case, it is possible to eliminate the coil 50a because the contacts 19a-46 will be normally connected by the movfable member 48 at any time the coil tb is deenergized. The larrangement as illustrated in FIGURE 6, requires only a momentary pulse in 'one or the other coils to establish, for an indelinite period, closing of the appropriate cont-acts.

As in the case of the other arrangements of Ithe invention described herein, multiple contact arrangements can be incorporated in relay designs (see FIGURES 1-3) and, if desired, the movable member 48 need not be part of an electrically conducting circuit (see FIGURE 4). Re- `erring now to FIGURES 7A, 7B Aand 8, there is illustrated an `arrangement of the invention which can be used to provide a center-off action. The switch includes a housing 5l having a permanent magnet assembly 52 including a pair of inwardly inclined pole faces 52a and SZb. Mounted in a central recess 52C of Ithe magnet are a pair of vertically-movable, switch-actuating members 53a and 5311 having complementary, inwardly inclined upper ends 54a and `Slb on which rests a movable member i55, which is preferably circular, taking the form, for example, of a roller or a ball of magnetic material. In the central position illustrated in FIGURE 7A, the magnetic attraction between the movable member 5:3 and the magnet S2 imposes downward forces on the vertically movable members 53a iand 53h, urging them downwardly against a pair `of transverse supporting bars 56a and 56b carried by a yoke `S7. The yoke 57 rocks on pivots 53a and Sb (FIGURE 8) extending outwardly therefrom and supported in the housing of the switch. The two vertically movable members 53a and 53D are also relatively movable so that one m-ay slide vertically relatively Ito the other as shown in FIGURE 7B. This 4relative vertical movement occurs when the yoke assembly 57 is rocked clockwise, as in FIGURE 7B, or counterclockwise. In the former case, the member 53]: will be lowered and the member 53a raised, thereby freeing the movable member 55 for movement to the right toward the pole tace 52b and at the same time imparting a push-ing force thereto. The magnetic forces then come into play to urge the member toward the pole face 52b.

Disposed above the pole faces 52e and 52h, on either side of `the movable member S5, are contact elements 59a and 59h supported from above in the housing. The contact elements are disposed relatively to the diameter of the -movable member 5S and to the raised positions for the actuating members 53a and 53h, so that the member 55 will wipe and firmly seat itself in contact-closing position. The angle formed by the working face 54a of the actuating element 53a, and of the contact element 5911 also controls the wiping and seating action which, in conjunction with the magnetic attraction between member 5S and the magnet 5i, establishes the contact pressure.

The electrical circuit includes terminals lia and 6lb connected respectively to the contact elements 59a and 59h and a terminal 61h (FIGURE 8) connected to the pivot SSb by a conductor 62. The pivot shaft SS is electrically connected to the transverse supporting bars 56a and 56k which support the actuating members 53a and 5311, the latter four elements all being electrically conducting. Thus, when the yoke 57 is rocked in a clockwise direction, as seen in FIGURE 7B, the movable member 55 will establish an electrical connection between the terminals 60b and 61h. When the yoke is rocked in a cou-ntcrclockwise direction, the circuit will be completed between the contacts 66a and lb. Each time the yoke 57 rocks, the supporting bars 56a and S611 wipe on the lower surface of the members 53a and 53]). When the yoke is in a horizontal position, as seen in FIGURE 7A, both circuits are open. Y

If desired, the central position for the movable member 55 can be utilized as a `closed-contact position for a switch utilizing the elements 53a and 53b as the contacts. rIo this end, the inner sliding faces of the elements 53a and 53b are insulated either by spacing the two elements apart, or as illustrated in FIGURE 7A, by applying insulating layers 64a, 64b, such for example as nylon or Telion to the sliding faces. In this arrangement, the yoke 57 is so arranged that one of the supporting bars 56h is electrically connected to the pivot 58h by the conductor 63, and the other bar 56a is connected to the pivot 58a by a conductor 65. The pivot 53a is connected to the terminal 61a by the conductor 66 and the pivot SSb is connected to a terminal 6lb by the conductor 62. If it is desired to use a switch merely as a center-off switch, the terminals 61a and `ttlb can be bridged. When it is desired to use the switch with a supplementary set of contacts, the bridge is opened and the terminals 61a and 61h utilized as a switch connection, wherein actuation of the yoke, either in a clockwise or counterclockwise direction, opens the circuit between the terminals 61a and 6119 while closing one or the other circuits between the terminals 69a-61a or 69h- 61k.

The switch assembly can be actuated in any one of several ways by rocking the yoke 57. This can be accomplished by driving through the pivots Stia-58h or, as illustrated in FIGURE 7A, by the use of a bat handle actuator 68 pivoted to the housing at 69 and having its inner end 7&9 slidably received in a vertical channel 71 carried on the underside of the yolk 57. In operation, the handle 68, when disposed in its center position, as indicated in FIGURE 7A, will hold the yoke 57 in its horizontal position. To augment this position, it is preferred to provide a detent at the pivot 69. Swinging the handle 6g to the right, as indicated in FIGURE 7B, rocks the yoke in a clockwise direction and the over `centering or toggle-like action of the movable member 55 will afford a positioning force for holding the handle in position.

The inwardly sloping surfaces 54a and 54h `of the actuating members tend to hold the movable member 55 stably in its central position. Any tendency of the member 55 to move away from its central position while actuating members 5351 and `53h remain in their neutral positions will require that the movable member increase its distance from the pole pieces of the magnet. Thus7 the magnetic forces also contribute to stabilization in the central position. If desired, this magnetic holding force can be augmented by including an extension of the permanent magnet upward along the center axis of the switch beneath the movable member, this extension passing through the yoke 57 and through suitable openings in the actuating members 53a and 5319. Also, a positioning abutment 67, preferably formed of non-magnetic material, can be permanently mounted on the vertical axis of the switch directly above the movable member 55 which blocks movement of the member oitof the actuating members 53a and 5311 while the latter are in their neutral or horizontally matched positions. When the switch is actuated, however, causing one of the actuating members to move downward, the movable member is free to shift without engaging the abutment 67. Similarly, anchoring abutments 67a and 67b ycan be provided on the inner surfaces of the contact elements 59a and 59h respectively to block movement of the movable member out of either of its contact closing positions.

The center-olf arrangement of FIGURES 7-8, while affording a central position for the movable member and hence a more flexible switch action, tends for some configurations to lack the strong magnetic toggle or snap action of the switch constructions of FIGURES l-6. Referring to FIGURES 9 and l() there is illustrated a switch 72 which incorporates both a center-off position as well as stronger snap action to the left and to the right of center. The switch 72 includes a housing 73, an actuator or handle 74 pivotally mounted in the housing, contact terminals 75a, 75l; and 75C and an actuating mechanism which selectively, through snap action, closes the circuit either between the contact terminals 75g-'75e or the contact terminals Sb-S/c. Mounted within the housing 72 is a xed magnetic assembly including a pair of permarient magnets 75 and 77 having pole faces 76a and 77a bounding a central chamber 7S in which is mounted an actuating assembly indicated generally by the numeral 79.

The actuating assembly 79 includes a carrier arm il@ having a bifurcated tip Sl which receives a movable meinber 82 which is formed of magnetic material and which is preferably circular, the member d2 being loosely fitted between the arms of the bifurcated tip Sil. The carrier arm t? swings on a constraining pivot 83 supported in the housing 73 and electrically connected by a conductor 34 to the terminal 75e. As the carrier arm swings from its extreme lefthand position as illustrated in FIGURE 9 to its corresponding extreme righthand position, the movable member 82 is carried first out of contact with the Contact blade a of the terminal 75a and into engagement with the contact arm SSI) of the terminal 75h. The contact openings as well as the Contact closing motion occurs with attendant snap` action and passes through a stable or open circuit position at the center of its stroke.

To this end the actuating assembly '79, as best seen in FIGURE 10 includes, at the lower end of the carrier 83, a pair of interlock plates 86 and 37 of magnetic material. Both are constrained for pivotal movement by the shaft 83 which functions in the manner of the constraining elements or barriers 13, f3', 3S and 53 of FIGURES 1 8. Preferably the carrier arm Sti` is rigidly secured to the pivot shaft S3 to afford good electrical contact therewith. The interlock plates 86 and 87 are joined to each other by studs 88 and 89 which pass through enlarged openings 90 and 9i in the carrier arm to afford lost motion. In this fashion the interlock plates 85 and 87 are coupled to the swinging carrier arm Sil. The ends of both interlock plates S6 and 87, as well as the ends of the lower portion `of the carrier arm S0, are slotted as best seen in FIGURE 9. The slots 37a and Sb define three magnetic pole tips 92a, 92b and 92C in the righthand end of the interlock plate S7. rI'he interlock plate 86 is similarly contoured, as are the two ends of the interlock plate S7. Similarly the lower end of the carrier arm 8@ is formed with pole tips 93a, QSb, and 95C on its lefthand end as well as similar pole tips on its righthand end `(not shown). The several pole tips work in conjunction with the pole faces 76a and 77a of the permanent magnets 76 and 77.

The lower sides of the interlock plates 86 and 87 are notched to receive the working end 74a of the actuator or handle 74. Thus, as the handle 7d` is swung to drive the assembly 79 toward its central position, the movable member 82 remains in engagement with the contact 35a until such time as the central pole tips, of which the tips 92h and 93b are examples, come `under the influence of the attracting force of the flux in the pole `faces 76a and 77a. At the time the actuator assembly 79 snaps to its central position, it drives the member 32 away from the contact 85a. In a similar fashion, the member 82 can be snapped into engagement ywith the contact 85!) or back into engagement with the contact 85a to complete the electrical circuits.

In certain cases it is desired to apply additional magnetic force to hold the movable member in engagement with one or the other of its contacts. To this end, the permanent field magnets '75 and '77 can be formed with Slotted pole tips 94 and 95 which terminate adjacent the contacts 85a and SSI: respectively. The slotted pole tips receive a portion of the free end of the carrier arm Sti and thus allow the movable member 82, which is magnetic, to `be brought into close proximity with a pole face so that the magnetic forces augment those generated in the lower pole tips '76a and 77a. As in the case of the S arrangements of the switches described above, the use of a central terminal 75C connected to the pivot shaft 63 and hence to the movable member 82 through the carrier arm Sti, can be omitted by providing pairs of spaced apart contacts and terminals which are bridged by the movable member S2 at either end of its stroke, in the manner illustrated in FIGURE 3, for example. In such cases it is preferred to utilize a roller configuration for the movable member 82 which might otherwise take the form, for example, of a ball.

ln case multiple contacts are provided at each end of the stroke, it is preferred that the carrier arm 80, at least at its upper end, be formed of electrically insulating material.

It will be understood that various combinations of the features and structures described above and illustrated in the drawings can be incorporated in a given switch design, depending on the particular requirements for the switch. ln most cases a magnetic toggle action is provided which is strong and fast acting while requiring a minimum of mechanical parts, none of which is required to function as a spring. Also, while the invention has been shown and described in representative embodiments for purposes of illustration, it can take various other forms and arrangements and should not be regarded as limited except as defined by the following claims.

I claim:

1. An electrical switch comprising a housing, a magnetic assembly including at least a pair of complementary relatively movable magnetic parts, at least one of the parts having pole faces to which the other is relatively attracted, the other part comprising a switch member, constraining means including a barrier interposed in the path of relative movement to define, together with the mutual magnetic attraction of the magnetic parts, said barrier engaging the switch member in all positions of equilibrium, a plurality of positions of stable equilibrium for the relatively movable parts, actuating means to shift 4the parts between positions of equilibrium and electrical contact means controlled by the relattive movement thereof.

2. An electrical switch comprising a housing, a magnet assembly including at least a pair of complementary, relatively movable magnetic parts, one part having a pair of pole faces between which the other moves, said other part comprising a movable switch member, barrier means interposed between the pole faces and normally engaging `the switch member in all of its positions, at least a pair of abutment means flanking the movable switch member and disposed respectively adjacent the pole faces, said movable switch member having at least a pair of stable positions of equilibrium between the barrier and the respective abutment means, the switch member being held in said positions under the `influence of magnetic attraction of the proximate pole face and switch actuating means to shift the movable switch member between stable positions.

3. Apparatus as set forth in claim 2, said barrier means being movable to drive the movable switch member out of either of its stable positions to assume the other position.

4. Apparatus as set forth in claim Q, said movable switch member being circular, said barrier means comprising a relatively narrow edge engaging the movable switch member and over which the switch member rolls in assuming its stable positions, the switch member being unstably supported by the edge in the absence of the abutment means.

5. Apparatus as set forth in claim 2, said abutment means being inclined to define a Wedging action to support the movable switch member together with said barrier means.

6. Apparatus as set `forth in claim 2, said movable switch member, abutment means and barrier means' all being electrically conducting.

7. Apparatus as set forth in claim 2, including movable contact members supported in the housing and adapted to be engaged by the movable switch member to be driven into contact-closing positions.

8. Apparatus as set forth in claim 2, including electromagnetic means to shift the movable switch member between its stable positions.

9. Apparatus as set forth in claim 8, including a pair of electro-magnetic coils associated respectively with the stable positions of the movable switch member.

l0. Apparatus as set forth in claim 2, said movable switch member being circular and divided with a plurality `of laterally spaced, electrically conducting parts, a common support for said parts, and a plurality of electrical contacts associated respectively with said parts to be actuated thereby.

11. Apparatus as set `forth in claim 2, said movable switch member being circular and divided into a plurality of laterally spaced, electrically conducting circular parts each electrically insulated lfrom the next, a common support for said parts affording rotation and relative translation movement thereof, and electrical contacts associated with each of said parts to be actuated thereby.

12. Apparatus as set forth in claim 2, said barrier means including at least a pair of -relatively movable parts mounted for movement transversely of the flux path between the pole faces.

13. Apparatus as set lforth in claim 12, said barrier being mounted between the pole faces of the magnet and including a pair of relatively movable members movable transversely across the magnetic flux between the pole faces, said relatively movable barrier member defining on their upper surface a seat to receive and support the movable member in a stable central position between the pole faces, said switch actuating means being connected to vthe movable barrier members to establish relative movement to disable the seat for the movable member and to urge the member in the direction of one or the other pole faces to be captured by the magnetic attraction thereof.

14. Apparatus as set forth in claim 13, said relatively movable barrier members being movable in differential motion with one member retracting between the pole faces of the magnet and the other moving outwardly therefrom, said members each including an inwardly sloping face to define when the parts are side by side a concave seat for stably supporting the switch member, and to define singly an inclined ramp pitched toward a pole face.

15. Apparatus as set forth in claim 13, said movable switch member being circular, and an abutment above the movable switch member when seated on said barrier members to block the movement of the movable switch member from the seat in the absence of differential movement of the barrier members.

16. Apparatus as set forth in claim 15, said electrical contact means each including an abutment to block the movement of the movable switch member out of its stable position when the relatively movable barrier members are differentially displaced.

17. Apparatus ras set forth in claim 13, said movable barrier members and said switch member -being electrically conducting, means to electrically insulate one barrier member from the other, whereby the movable switch member, seated thereon, affords an electrical path between the barrier members, and electrical terminals connected to the respective barrier members, whereby a switch section is provided in addition to that afforded by the arrayed electrical contact means and the barrier.

18. Apparatus as set forth in claim 13, said switch actuating means including a pivot member supported generally between the movable barrier members and engaging the respective barrier members and engaging the respective barrier members on opposite sides of the pivot axis, and means to rock the pivot member to withdraw one movable barrier member between the pole faces and to extend the other outwardly across the flux path.

19. Apparatus as set forth in claim 18, said pivot member including ya pair of electrically conducting members slidably engaging the respective barrier members on a transverse surface thereof, said electrically conducting members being electrically insulated from one another, and a p-air of electrical terminals connected respectively to said electrically conducting members.

20. Apparatus as set forth in claim 18, said switch actuating means including a handle pivotally mounted in the housing, a pair of shoulders on the pivot member embracing the inner end of the handle, the outer end of the handle extending outwardly from the housing to form an actuating lever for the switch, whereby the central position of the handle holds the movable barrier member-s in side-by-side relationship to define a stable seat for the movable member and, when moved to one side or the other, differentially displaces the barrier members to urge the movable member toward one or the other of said pole faces to be seated thereadjacent in switch-actuating positions.

21. Apparatus as set forth in claim 2, sa-id permanent magnet being movably mounted in the housing, said barrier means being supported by the magnet.

22. Apparatus as set forth in claim 1, said constraining means comprising a pivot supported by the housing, one of said relatively movable parts comprising an elongated member centrally supported by the pivot and having pole faces at its ends, second pole faces on the other magnetic part, opposing and complementary to the respective pole faces on said one part, at least one pole face being formed with a plurality of sections to define a plurality of positions of stable equilibrium, said electrical contact means being controlled by said elongated member.

23. Apparatus as set forth in yclaim 22, including a switch member, a carrier for the switch member mounted on said pivot, and a lost motion coupling between the elongated member and the carrier member.

24. Apparatus `as set forth in claim 22, including a cir-cular switch member, a carrier for the switch member supported by said pivot, said switch member being movable in the carrier `in the Adirection of pivotal movement, electrical contact means being `disposed to -be engaged lby the switch member at extreme positions of pivotal movement of the carrier, and means connecting the elongated member and the carrier.

25. Apparatus as set forth in claim 24, including magnetic pole pieces disposed adjacent said contact means, said switch member being magnetic.

26. Apparatus as set forth in claim 25, said pole faces adjacent said contacts having openings to receive said carrier.

References Cited in the le of this patent UNITED STATES PATENTS 1,961,146 Harrington June 5, 1934 2,618,718 Dufling Nov. 18, 1952 2,641,664 Knutson June 9, 1953 2,665,344 Zozulin Ian. 5, 1954 2,688,063 Gromersall Aug. 3l, 1954 2,836,675 Kathe May 27, 1958 2,859,297 Reynolds Nov. 4, 1958 2,927,185 Bonnaire Mar. 1, 1960 

